In the medical field, magnetic resonance imaging (MRI) is a commonly used non-invasive technique to diagnose the medical condition of a patient. Typically, the MRI system operator places the patient within the central bore of large homogeneous magnetic field and the MRI system subjects the patient to a set of gradient magnetic fields and RF pulses. The MRI system measures the very small RF signals emitted from nuclei in the patient, and processes the information to reconstruct an image of the part of the patient's body in the MRI system. The images produced by the MRI have very small amplitude RF signal in the frequency range 50 to 150 MHz. The frequency depends on the strong fix magnetic field and the magnetic gradient fields.
The MRI magnet bore is small, especially in the head-coil, and induces claustrophobic feelings in many patients. The MRI system produces loud noises as the MRI system changes the gradient magnetic fields. These loud noises add to the anxiety and discomfort of the patient. Under these conditions, up to 20% of patients do not remain sufficiently still during the 20 to 60 minute process for a successful MRI image. As is known in the art, the MRI system operator may reduce or eliminate the patient's claustrophobic feelings and anxiety by providing the patient with some type of entertainment. The entertainment system calms the patient, distracts the patient from the MRI procedure, and results in more patients remaining sufficiently still during the MRI procedure for adequate image quality.
There are at least six critical areas that must be addressed when providing a patient with some type of entertainment in a MRI system. First, the strong fields generated by the MRI device must not prevent the normal operation of an entertainment system or cause the entertainment system to move in the MRI system's large magnetic field. Second, the large RF pulses from the MRI system must not harm or heat up the entertainment system. Third, the entertainment system must not emit sufficient RF energy to degrade the MRI image quality. Fourth, the Faraday shield used to contain the entertainment system's RF signals must not produce anomalies in the MRI image. Fifth, the entertainment system must fit within the MRI system and comfortably accommodate a wide range of patients. Sixth, the entertainment system must be affordable, reliable, and easy to use.
These critical areas also include competing considerations. It is appreciated that to address one critical area may detract from the performance of another critical area so that the results are not predictable especially when addressing two or more critical areas as discussed herein. Despite these constraints, inventors have designed many types of entertainment systems in an attempt to provide the patient with some entertainment. However, these attempts have failed to provide a self-contained entertainment system that is integrally used within an MRI during the operation thereof as in the present invention.
Features of prior art entertainment system that had little or no use in an MRI due to difficulties associated therewith include but are not limited a battery, video media, storage mediums, various electronics from computers, or otherwise, or combinations thereof. For example, the prior art generally taught that batteries may not operate safely in an MRI, because the eddy current may heat and discharge the batteries. It is appreciated that for an entertainment system to be truly self-contained, the entertainment system may be configured to read data from a storage medium (e.g., a memory card) and process the data into video signals. Such process of data, generally requires processing millions of data with critical time and voltages. It is appreciated that the large magnetic field produced by the MRI may undesirably affect electrical circuits, such magneto resistance, and hall-effect voltages. As such, the prior art provides insufficient teachings that storage mediums such as a memory card and/or the corresponding circuits to read the data and create video signal may be operable in the high magnetic field of a MRI. However, the present invention attempts to solve these problems and others by providing a self-contained entertainments system.
Exemplary entertainments systems include: U.S. Pat. No. 4,901,141 to Costello discloses video systems that supplied video images through optic fibers to the patient. U.S. Pat. No. 5,134,373 to Tsuruno et al. supplies images via optical transfer means from a screen. U.S. Pat. No. 5,861,865 to Anand et al. generates images on LCD displays outside the magnet, which the patients see with mirrors and prisms. These systems retrofit the MRI system with the optical fibers or optical transfer scheme, which is rather expensive to install. The long length of fiber from the MRI control room to the MRI system attenuates the image and degrades the image quality. U.S. Pat. No. 5,076,275 to Bechor et al. generates an image behind the MRI device and has a mirror for reflecting the image to the patient. These systems do not readily accommodate different positions of the patient. The patient is still aware of the surrounding MRI system with these entertainment systems; thus, the systems may not adequately distract the patient. In addition, the lighting in the MRI magnet room can make the display more difficult to watch.
These entertainment systems require expensive installations in the MRI magnet room and bring the entertainment signal through the MRI magnet room Faraday shield. All entertainment systems that bring in the signal by cables have the potential problem of snagging and damaging the long cables. Many patients wear glasses to correct their vision. Typically, the patient cannot wear his or her glasses in the MRI system because the glasses contain ferromagnetic material, such as steel screws. Many of the systems described in prior art do not allow for optical correction.
U.S. Pat. No. 5,412,419, U.S. Pat. No. 5,627,902, and U.S. Pat. No. 6,463,316 disclose bringing the audio to the patient pneumatically through flexible pipes. Long lengths of pipe to bring an audio signal from outside degrade the audio signal quality by attenuating the high frequency audio signal. U.S. Pat. No. 5,877,732 discloses generating the audio with piezoelectric speakers and bringing the audio to the patient with a short length of pipe. U.S. Pat. No. 5,577,504 to Salloway et al. discloses an entertainment system that includes noise cancellation and non-ferromagnetic headphones.
Prior entertainment systems for use in an MRI system are complicated because they transmit the entertainment media from the MRI control room to the MRI magnet room via penetration of the room shielding. These prior entertainment systems require modification to standard, pre-existing MRI facilities. These MRI facilities modifications are expensive and stop operation of the MRI facilities during modification.
Portable video players are much less expensive than the custom entertainment system developed in prior art for use with an MRI system. Portable video players require no costly installation at the MRI facility. These consumer portable video players are the desired affordable self-contained entertainment systems. However, these consumer portable video players may be unsuitable for use in a MRI system because they contain ferromagnetic materials, they emit RF energy that can interfere with a MRI image quality, they may be affected by the RF pulse of a MRI system, they may not be securely attached to the user allowing their use in any position, or otherwise.
Thus, the present invention provides a self-contained, portable entertainment system for use by a patient within a magnetic bore of an MRI device during the operation thereof, wherein the entertainment system at least assists in overcoming one of the aforementioned drawbacks or other drawbacks.
It is appreciated that various entertainment system designs have been provided in U.S. Pat. Nos. 5,134,373, 5,412,419, 5,414,459, 5,577,504, 5,627,902, 5,861,865, 5,864,331, 5,877,732, 5,076,275, 6,463,316, 6,774,929, 4,901,141; International Patent Applications WO2006132542, WO2005119284, JP2002102203A, and DE20021037924; and Published References “Electromagnetic Scattering” by Piergiorgio Uslenghi, “NMR, A perspective on imaging” by General Electric, “Electromagnetic Analysis and Design in Magnetic Resonance Imaging” by Jianming Jin, and “Micro-loopless Antenna for High Resolution MR Imaging of the Brain” by Warren Grundfest, which are herein incorporated by reference for all purposes.